From 9858403a9521fbda24f9986e6d59cfa91c8cae0f Mon Sep 17 00:00:00 2001
From: Jordan Sherer <jordan@widefido.com>
Date: Wed, 6 Nov 2019 14:11:39 -0500
Subject: [PATCH] Fix spectrum display to reset cumulative display every period

---
 mainwindow.cpp | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/mainwindow.cpp b/mainwindow.cpp
index 2172640..f682e10 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -2618,8 +2618,22 @@ void MainWindow::dataSink(qint64 frames)
 
     /// END IHSYM
 #else
-    m_ihsym=m_ihsym%(m_TRperiod*RX_SAMPLE_RATE/m_nsps*2);
+    // make sure the ssum global is reset every period cycle
+    static int lastCycle = -1;
+    int cycle = computeCurrentCycle(m_TRperiod);
+    if(cycle != lastCycle){
+        qDebug() << "period loop, resetting ssum";
+        memset(ssum, 0, sizeof(ssum));
+    }
+    lastCycle = cycle;
+
+    // cap ihsym based on the period max
+    m_ihsym = m_ihsym%(m_TRperiod*RX_SAMPLE_RATE/m_nsps*2);
+
+    // compute the symbol spectra for the waterfall display
     symspec_(&dec_data,&k,&k0,&ja,ssum,&trmin,&nsps,&m_inGain,&nsmo,&m_px,s,&m_df3,&m_ihsym,&m_npts8,&m_pxmax);
+
+    // make sure ja is equal to k so if we jump ahead in the buffer, everything resolves correctly
     ja = k;
 #endif